Pregnant mice (CD-1 strain) were exposed to 2.45-GHz microwave radiation at power density levels of 5,21 and 30 mW/cm to the second power. The group exposed to 5 mW/cm to the second power were irradiated for eight hours per day (4 hours exposure - 1 hour in home cages for food and water - 4 hours exposure) from day 1 to day 15 of pregnancy. For the 21 and 30 mW/cm to the second power exposure, two different groups of animals were irradiated for different portions of pregnancy, days 1-6 and days 6-15. Groups were also exposed to elevated temperature to simulate thermal stress (30 degrees centigrade for the 21 mW/cm to the second power group and 31 degrees centigrade for the 30 mW/cm to the second power group). Exposure to power densities of 5 mW/cm to the second power (SAR is approximately 5.2 mW/g) and 21 mW/cm to the second power (SAR is approximately 22.3 mW/g) did not produce any adverse maternal or embryofetal effects. At exposure to 30 mW/cm to the second power (SAR approximately 32 mW/g) during days 1-6 a significant decrease in implantation sites per litter and average fetal weight was observed. Exposure to 30 mW/cm to the second power during days 6-15 resulted in a slight increase in the number of malformed fetuses (3.1 percent in the microwave exposed group, 1.7 percent in the 31 degrees centigrade elevated temperature group). The predominate malformation was cleft palate.